Safety and belief valve



Jan. 1s, 1949. E, C. gummi, 2,459,553

SAFETY AND RELIEF VALVE Filed OCT.. 31, 1945 Patented Jan. 18, 1949 SAFETY AND RELIEF VALVE Earle C. Sullivan, Bridgeport, Conn., assignor to General Electric Company, a corporation of New York Application October 31, 1945, Serial No. 625,900 2 Claims. (Cl. 137-53l While not limited thereto, this invention is par-- ticularly useful in pressure cookers.

Pressure cooker safety and relief valves have been provided which are set to open at a fixed steam pressure. Some have been arranged so that they also can be operated to vent the air from the cooker at the start of the cooking opera-- tion, and also to\blow off the pressure at the end of the cooking` operation. A commonl arrangement was to use 4a weight for holding the valve closed against the cooker pressure, the valve being forced from its seat against the force of the weight to open and relieve the pressure when the pressure acting on the valve attained a predetermined high value. ated at the lowest desired pressure. Higher pressures wereobtained by using separate heavier weights, or by adding additional weights to the minimum weight. Air or steam could be vented by manually lifting the weight or weights.

This invention contemplates an improved safety and relief valve having but a single iixecl4 weight, but constructed and arranged so that several selected operating pressures can be obtained. Also it contemplates such an improved construction in which air can be vented, and the pressure released from the cooker when it is desired to do so, all in a simple, safe and reliable manner.

, In accordance with this invention, the valve is held in its closed position by a single weight against the pressure of the cooker. 'The valve is constructed and arranged so that the eifective area thereof which is acted upon by the pressure is variable. By adjusting this area the valve is caused to operate to release at different cooker pressures.

Also, the valve is constructed and arranged so that the area can be adjusted by the simple manual operation of a control knob and function so that the cooker can be purged of air, or the steam pressure released therefrom by an operation of the control member.

For a more complete understanding of this invention, reference should be had to the accompanying drawing in which Fig. 1 is a side elevation of a pressure cooker embodying a safety and pressure relief valve arranged in accordance with this invention, parts being shown in section so as to illustrate certain details of construction; Fig. 2 is a vertical sectional view through the valve The weight chosen oper' structure of Fig. 1, this view being drawn to a larger scale than Fig. 1; Fig. 3 is a fragmentary side elevation of a part of the structure shown in Fig. 2 and at right angles to the corresponding parts shown in that iig'ure; Figs. 4, 5 and 6 are fragmentary sectional views illustrating the valve structure set to operate at different predeter-4 mined cooker pressures; and Fig. 7 is a perspective view of a portion of the valve structure.

Referring to the drawing, this invention has been shown in one form as applied to a pressure cooker comprising a cooking vessel I shown as a relatively deep saucepan. The vessel is provided with a handle 2. It also is provided with a cover 3 which is provided with a handle 4. I have illustrated the cooker provided with a cover structure arranged as described in the Vscher Patent No. 2,282,011, dated May 5, 1942. Briefly, this comprises a peripheral sealing edge tl on the cover which seats against an inturned flange 6 at the top of the cooker vessel, the lid being held in its sealing relation with the flange by means of a hook l carried by the cover handle 4 and engaging the vessel handle 2, as shown in Fig. 1.

The safety and pressure relief valve structure arranged in accordance with this invention is mounted in the center of the cover 3, and comprises a valve housing 8 of cylindrical form and having an integral bottom wall 9. The diameter of the lower part of the bottom wall 9 is reducedl somewhat so as to define a reduced extension l0 joined to the housing 8 by a shoulder il. The reduced part lil is inserted through an opening l2 provided for it in the center of the cover 3, and it is secured to the cover by a nut i3 threaded upon a further reducedfsection i4 extending `down from the bottom wall 9. The joint between the valve structure and the cover 3 is made pressure proof by means of a pair of elastic sealing washers Ma, one interposed between the shoulder Il and the top surface of the cover, and the other interposed between the bottom surface of the cover and the nut I3, all as shown most clearly in Fig. 2.

` The discharge port of passageway l5 is conthe sleeves 2| and ward the seat by means vof to a shaft 3| 31 and 38 in which trolled by a lvalve structure' I3 comprising an inner valve rod 20, an outer sleeve member 2| in telescopic relation with the rod. and a second outer sleeve 22 in telescopic relation with the sleeve 2|. The lower ends of the three members 20, 2| and 22 form valve structures cooperating with the conical seat I3. As shown, the rod has a tapered valve seat section 23 at its lower end, while 25 respectively attheir lower ends, all three seat sections being f ormed as sections of a cone complementary to the conical seat I8. i

The valve sections 20, 2| and 22 are biased toa fixed weight 23 in the form of a flat wide disk, as shown. This weight is threaded upon .van enlarged cylindrical section 21 formed at the top of the outer sleeve 22. This outer sleeve 22 also is provided with an enlarged cylindrical part 28 located in the top of the chamber I1. This section 23 flts loosely in the chamber so as to provide a`slight clearance space 29 between the two members this space 29 22, have seat sections 24 and constitutes a port through which the gases of the pressure cooker vent to the atmosphere after being released by the valve structure.

The valve members 20, 2|' and 22 are selectively operable away from the valve seat cally controlled means in order to vary lthe effective area of the valve which is exposed to the cooker pressure. For this purpose 'a cam 30 is provided. This cam is mounted upon and secured which is Journaled in spaced upright ears 32 positioned on opposite sides of the cam and formed on the upper side of the weight 26, as shown. The cam is enclosed by a protective housing 33, and it is operated by a knob 34 located on the exterior of the housing and attached to the shaft 3i.

The cam 30 is provided with a sections 35 and 36 pair oi' operating provided respectively with races pins 39 and 49 on the respective valve sections 2| and 23 are received. As shown, the upper end of the sleeve 2| is provided with a recess 4Iwhich receives the cam sections 35 and 36, 'and in which the pin 39 is located so race 38.

., faces 42 and 23 and thereby I6 by mechanicause the central and the area of the thereby lpermitting only the sleeve the valve is opened to release the pressure into the chamber I 1 and out through the opening 29.

To` obtain a. lower pressure the knob 34 is moved counterclockwise (Fig. 3) to an intermediate pressure position in'which the cam races 31 and 38 sleeve 2| only to contact the valve seat'll. while the rod 20 and the outer sleeve 22 are elevated from the seat, all as shown in Fig.

4. The effective area of the valve now exposed to the cooker pressure is the sum of the area 42 seat section 23 on the bottom of the rod 20. Since the combined area is greater than the area 42. a lower cooker pressure is required to elevate the valve structure against thei'orce of the weight 2l to release the cooker pressure.

erating the knob 34 counterclockwise to a lower pressure Position; this operation causes the races 31'and 33 to elevate the rod 20 and the sleeve 2|,

the valve'seat I3, as shown ln Fig. 5. This adds the conical surface 24 of the sleeve 2| to the surgives the maximum to the cooker presthe lowest pressureof the the) time the valve opens to surface of the valve exposed sure. Consequently, cooker is obtained at release. l

Preferably, a pressure scale 43 reading in pounds per square inch will be provided on the outer wall of the casing 33 opposite the knob 34 to assist in setting the knob.

In startlng'up a pressure cooker from a cold condition it is desired to vent entrapped heated air from the cooker; and at the end of the cooking operation. it is desired to blow off the steam pressure. I accomplish both of these operations by' forming in :the outer valve sleeve 22 a vent .port 44 adjacent its lower end, Normally, this When the operating knob 34 is rotated ltoperates the camv 30 so as to selectively move the valve sections 20. 2| and 22 into and out of contact with the valve seat I8. When the knob 34 is in its position shown in Fig. 3, it sets the valve and to lift the sleeves 2| and 22 vout of contact therewith. It will be understood that the cam slot 38 will be so shaped that when the knob 34 is rotated clockwise to its high pressure position of Fig. 3 it will first cause the rod 20 to engage the valve seat I8, and then upon its continued mois closed by the sleeve 2|, but wheny it is desired to either bleed the air from the cooker or to blow the steam olf from it, the knob 34 is operated to a position indicated "0" on the pressure scale 43. When the knob is moved to this position the cam 30 is operated to elevate the rod 29 and the sleeve 2| to open the passageway i5 to the sleeve 22 and to uncover the port 44, thereby permitting the cooker to vent through the opening 44.

The building up of -pressure in the cooker tends to force ther valve weight 28 into the air and out of its proper position. This is prevented by providing the bottom of the weight 26 with a fiat horizontal smooth surface 45 which is relatively large in area, and providing opposite it a second similar surface 46 fixed to the valve housing 8. These two surfaces are relatively close together so as to define a narrow space 41 between them. This space at its central part communicates with the vent passageway 29 and at its outer periphery opens to the atmosphere. The valve structure is such that just after the valve opens the seat I6, the cylinder 23 clears the upper edge of the bore 23 to vent to the atmosphere. Gases escaping through the bore 29 pass into the narrow space 41 at its central part and then move radially the phenomena known as the Bernoulli effect.

value in order to overcome the weight 28 before 75 This briefly is that in a flowing stream the sum of the velocity,

A still lower cooker pressure is obtained by opl 22 to engage one point is always equal to their sum at any other point removed in the direction of flow from the rst point, neglecting the loss due to friction between these points.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that various changes and modications may be made without departing from my invention in its broader aspects and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A pressure relief valve comprising a housing having a pressure relief passage one end of which is adapted for connection with a source of pressure, and the other end of said passage constituting a release port, a valve seat at said other end opening intosaid port, a valve seating on said seat to close said port, said valve having an outer tubular member having at its bottom end a sealing section complementary to said seat and adapted to seatithereon. a fixed weight attached to said tubular member biasing it into engagement with said seat, a plurality of inner telescopically arranged valve seat members mounted within and telescoplng with said tubular member and having at their lower ends sealing sections complementary to said seat and adapted to seat thereon in sealing relation, and operating means for selectively moving said tubular member and said inner members vertically out of engagement with said seat so as to vary the effective area of said valve exposed to the pressure in said passage.

2. A pressure relief valve comprising a housing having a pressure relief passage one end of which ls adapted for connection with a source of pressure, and the other end ot said passage constituting a pressure release port, a valve seat at said other end opening into said port, a valve seating on said seat to close said port, said valve having an outer tubular member having at its bottom end a sealing section complementary to said seat and adapted to seat thereon, means biasing said tubular member into engagement with said seat with a substantially constant predetermined force, a plurality of inner telescopically arranged valve seat members mounted within and telescoping with said tubular member and having at their lower ends sealing sections complementary to said seat and adapted to seat thereon in sealing relation, operating means for selectively moving said tubular member and said inner members vertically out of engagement with said seat so as to vary the effective area of said valve exposed to the pressure in said passage, and said outer tubular member having a vent port in its side wall above its bottom end, said vent port normally being closed by the adjacent inner member and opened when said adjacent inner member is moved vertically to a predetermined position by said operating means.

EARLE C. SULLIVAN.

REFERENCES CITED The following references are of record in the file of this patent:

valve seat i 

